This invention relates to vehicle powertrains and, more particularly, to vehicle powertrains having a fuel cell power source and an electro-mechanical multiple range transmission wherein the transmission employs two motor/generator type mechanisms, two planetary gearsets, and two torque-transmitting mechanisms.
Vehicular powertrains are employed to provide traction drive forces for many types of vehicles. In most of the present vehicles, a powertrain employing an internal combustion engine or other mechanical power source is combined with either a multi-speed power transmission or with a variable speed power transmission. The variable speed power transmissions employ either hydraulic devices, motor/generator devices, or continuously variable belt-type transmissions.
Each of these transmissions includes a mechanical power source to supply the majority of the input power for the powertrain. More recently, electrical drive mechanisms have been suggested wherein a plurality of storage batteries or electrical energy storage devices are employed to supply power to electric motors which operate in series with a gear mechanism to provide substantially a single range of operation. Even more recently, it has been considered that fuel cells can be utilized as a power source to supply electrical power to the electric motors. Again, these powertrains incorporate a series-type arrangement between the driving electric motors and the output of the transmission.
The present invention seeks to improve upon powertrains employing fuel cells as a power source.
It is an object of the present invention to provide an improved powertrain, wherein the fuel cell supplies power to a pair of motor/generator units, which are interconnected through a power of planetary gearsets to establish a drive connection with a transmission output shaft.
In one aspect of the present invention, one of the motor/generator units supplies driving forces to the power take-off unit, which operates a plurality of fan members for cooling the fuel cell power source.
In another aspect of the present invention, the power take-off unit also supplies drive mechanisms for hydraulically operated devices, such as steering and brakes for a vehicle.
In yet another aspect of the present invention, the two planetary gearsets are interconnected together and with the transmission output shaft.
In still another aspect of the present invention, a pair of torque-transmitting mechanisms are employed to control the operating condition of one of the planetary gearsets.
In a further aspect of the present invention, an energy storage and retrieval assembly is employed to provide additional power when maximum vehicle performance is required.
In a still further aspect of the present invention, an electronic control unit is employed to provide electrical connections and communications between the fuel cell, the two motor/generator units, and the batteries.
In yet a still further aspect of the present invention, the electronic control unit employs a programmable digital computer to control the operating conditions of the electrical portion of the powertrain.
In a yet still further aspect of the present invention, each of the planetary gearsets includes a sun gear member, a ring gear member, and a planet carrier assembly member, wherein the sun gear member of the first of the planetary gearsets is continuously interconnected with the planet carrier assembly member of the second planetary gearset, and with the transmission output shaft.
In still yet another aspect of the present invention, the ring gear member of the first planetary gearset is continuously connected with the power take-off unit.
In another aspect of the present invention, the planet carrier assembly member of the first planetary gearset is connected with one motor/generator unit, and the sun gear member of the second planetary gearset is connected with the second motor/generator unit.
In yet still another aspect of the present invention, the ring gear member of the second planetary gearset is selectively connectible with a stationary housing to provide a reaction member within the second planetary gearset through one of the torque-transmitting mechanisms, and selectively connectible with the transmission output shaft to establish a 1:1 drive ratio in the second planetary gearset through a second torque-transmitting mechanism.
In a yet still further aspect of the present invention, the motor/generators share power equally throughout the operating range of the transmission and the power take-off unit.